This invention relates to an assembly for attaching sheet material to a support, and an example of which is the construction of a temporary or semi-permanent greenhouse structure comprised of a framework over which sheet material, such as polyethylene film, is stretched to form an enclosure. Frequently these structures are provided with various temperature and other atmospheric controlling devices which require that the enclosure be relatively tight to seal out the outside weather. However, these structures must also be of a nature that permits at least partial disassembly during the off-season which at the same time being low cost from both the standpoint of materials used and the labor involved in assembly and partial and complete disassembly.
In this connection, it has become a readily accepted practice to employ the use of polyethylene film which heretofore has been attached to a framework through the use of laths or strips of wood which are nailed to the support in such a manner that the film disposed between the lath and support are thus held in place. This has been less than satisfactory, however, because of the tendency for the plastic material to tear at the point that the nails are driven through the laths and the film and because of the wind action which tends to cause the film to pull loose thus making the structure less than airtight in addition to damaging the polyethylene film.
Another method has been devised to secure the film and involves the use of interlocking components for clamping the plastic material therebetween and with one of the components being adapted or supported from the greenhouse structure and the other component being releasably interlockingly engaged with the first component. These interlocking components, however, are less than satisfactory inasmuch as the two components thereof must be disassembled by the use of specific hand tools. Such interlocking components have also been less than satisfactory inasmuch as once a film portion is secured in place, no adjustment or repositioning of the film can take place in order to smooth out, readjust or tighten the film over the structure.
Examples of two-piece interlocking material anchors as well as other anchors utilizing some of the general structural and operational features of the instant invention are disclosed in U.S. Pat. Nos. 946,312, 3,612,539, 3,803,671 and 3,965,546.